Description: Although modestly effective treatments exist for alcohol use disorders (AUD), many individuals relapse to heavy alcohol use after completing treatment, suggesting the need for a better understanding of factors that contribute to successful outcomes. Whereas much of the focus in past studies has been on identifying what treatments work for AUDs, only recently has there been a focus on why particular treatments work, and the mechanisms by which treatment leads to changes in drinking. This focus on mechanisms of behavior change (MOBCs) has the potential to not only allow for an accumulation of knowledge about the process by which treatment leads to better outcomes, but also may lead to the development of new treatments or modifications of existing treatment approaches that target empirically supported mechanisms known to lead to change. Existing research has focused on potential mechanisms including alcohol cue reactivity, affect regulation, and behavioral control, but these constructs have largely been tested using self-report measures, and there is a noticeable paucity of studies that examine these mechanisms from a neurocognitive perspective. To address this gap in knowledge, the proposed study will examine MOBC at multiple levels including self- report, behavioral performance, and neural network engagement, with a focus on the function of the lateral and medial frontal control networks, striatal based reward networks, and amygdala networks underlying emotional reactivity. One hundred eighty treatment-seeking individuals with an AUD will be randomized to receive either 8 weeks of Cognitive Behavioral Treatment (CBT) or Mindfulness Based Treatment (MBT) after receiving 4 weeks of a platform treatment that focuses on enhancing motivation to change. To establish the temporal relationship between changes in drinking and changes in these MOBCs, patients will be assessed at: (a) baseline; (b) four weeks into treatment; (c) immediately post-treatment; and (d) 9- and 15-months post- baseline. Self-report measures and behavioral tasks will be administered at monthly intervals during treatment; and fMRI will be collected at baseline, and at 3, and 9-months post baseline. Relationships between changes in drinking and changes in the proposed MOBCs will be examined using advanced mixed modeling techniques that have been pioneered by the research team. Further, the project will leverage data collected in a separate project examining MOBC in a non-treatment seeking sample using the same measures collected at similar timepoints. By identifying MOBCs of CBT or MBT that differentially contribute to changes in drinking, the proposed project will not only derive a deeper understanding of successful behavior change, but also may inform the development of novel treatments for AUD. In addition, by identifying neurocognitive factors predictive of successful change, it may be possible to utilize this knowledge to match specific treatments with particular patient neurocognitive profiles.